The NHS Confederation, which represents health trusts, made the critical intervention calling for “some more sophisticated arguments,” as it prepares a submission proposing major changes to the health and social care bill, in an attempt to broker agreement.

The influential organisation will say that the NHS should only be forced to introduce competition in situations where there is evidence would improve standards for patients. It proposes an extra duty, which would mean services could also be made to merge, or work together, if that was more likely to deliver improvements.

Mike Farrar, the newly appointed head of the NHS Confederation, expressed frustration that tensions within the Coalition have left those working in the NHS with no sense of direction.

Last week, Andrew Lansley, the beleaguered health secretary, was cheered by back-bench Tory MPs who are furious that Nick Clegg and fellow Liberal Democrats have been openly “trashing” the legislation they backed in Parliament.

Mr Farrar said: “We live in a democracy, we welcome debate but to embark on this sort of change we do need a clear political mandate – and so far it has been quite unclear. We are realistic about working in a politicised environment, but this is about as extreme as it gets. “

He added: “We need to hear some more sophisticated arguments, and get beyond the politics of this to the practicalities. On the ground, we are desperate to make sense of this, and to make it work.”

The paper will say decisions about local markets in health care should be taken on the basis of a “public interest test” demonstrating that a change would improve patient care. The model would mean that while competition might be introduced for some services – such as hip operations, where it has been shown to drive up standards – in other specialisms, such as stroke treatment, where better results are achieved by large centres dealing with high numbers of patients, units might instead be ordered to merge.

Mr Farrar said: “We do not believe it is right that any individual should be left to get health care from a poor quality of service. Competition should still be a weapon in the armoury but so should consolidation, and co-operation, which can equally improve the care patients receive, depending on the particular circumstances.”

“We want to apply a public interest test; so that if a decision was challenged, the question asked is 'Is it reasonable that this decision was taken, was it in the interests of patients?’ rather than simply, 'Did it promote competition?’”.

The changes, which will be submitted to a review of the reforms on Wednesday, which have been “paused” by David Cameron, support the need for NHS reform, but call for a series of significant amendments to be made to the legislation.

As well as proposing a dual duty of competition and collaboration on regulators, it will say changes to hand powers to new groups of GP consortia should be made at a “sensitive pace,” and propose ways to strengthen their accountability.